DESCRIPTION: The tissue matrix is the dynamic front that links the skeletal networks of the nucleus and the cytoplasm with the extracellular matrix. These studies are designed to test the hypothesis that nuclear matrix protein 4 (NMP4) a novel, PTH-responsive osteoblast nuclear matrix factor, plays a role in promoting expression of the alpha 1 chain of type 1 collagen (COLA1) in osteoblasts. The principal aim of these studies is to purify NMP4 for the purpose of obtaining microsequencing data needed to generate antibodies to thi novel protein. Nuclear matrix proteins will first be extracted from UMR-106 cells using a standard sequential extraction protocol. NMP4 will then be isolated using DNA-affinity chromatography and double-stranded oligomers to th -1574 to -1555 nt segment of the COLA1 promoter (site B), that is coupled to a crosslinked agarose support. After elution, NMP4 will be further purified by SDS/PAGE, excised and microsequenced for antibody production. The availability of probes to this nuclear matrix protein will 1) facilitate further studies on the role of NMP4 in mediating a novel nuclear pathway for PTH action, 2) delineate the differences between the in vitro and in vivo effects of PTH on bone formation, and 3) clarify the cellular basis for the anabolic actions of PTH on bone.